What is typhoid, how is it spread, and how is it treated?
Typhoid fever is caused by bacteria ( Salmonella typhi ) and usually manifests with a combination of fever, chills, headache, weakness, loss of appetite, abdominal pain, body aches, and cough. Small, red spots appear on the chest, abdomen, and back of about 20 percent of white patients. Constipation is common in older children and adults, but diarrhea may occur in younger children. The germ that causes typhoid fever can stay in the bloodstream or cause infections in the bones, liver, or lungs. Typhoid fever can cause a life-threatening perforation of the intestines and massive bleeding. Antibiotics are available to treat typhoid fever. Unfortunately, the disease is becoming resistant even to the newest and best of the antibiotics. Without treatment, about 30 percent of patients die.
Humans shed the bacteria in their stool, which then contaminates water or food. Susceptible persons later consume the contaminated water or food. The spread of this disease directly from one person to another is uncommon.
Two to 5 percent of untreated typhoid fever patients shed the bacteria in their stool for years and years and so, like “Typhoid Mary,” they become a source of infection for many other persons. They are called chronic carriers.
Typhoid fever is common on the Indian subcontinent and in developing countries in Latin America, Asia, and Africa. Worldwide, an estimated 16 million cases and 600,000 deaths are reported each year from typhoid fever. About 1.3 out of 500,000 U.S. citizens got typhoid fever while traveling abroad in the early 1990s.
How effective is typhoid vaccine, and who should get it?
There are three different typhoid vaccines: one is given by mouth (Ty21a) and two are injected (the ViCPS, or “Vi” form, and a parenteral inactivated, older form). Each protects roughly 50 to 80 percent of recipients. The schedule depends on the age of the recipient and on the form used. The vaccine given by mouth requires careful adherence to a somewhat complex eight-day regimen. The “Vi” form requires one injection initially. The other injected form initially requires two doses separated by at least four weeks.
No country currently requires typhoid fever vaccine for entry. However, because there is a risk of typhoid fever for U.S. travelers, the vaccine is recommended for those who will have prolonged exposure to potentially contaminated food and drink while visiting the Indian subcontinent, or developing countries in Latin America, Asia, or Africa. Vaccination is of particular value for persons who will be visiting smaller cities, villages, and rural areas.
Vaccination should not be used as a substitute for careful avoidance of contaminated food and beverages.
Who should not get the vaccine?
Persons with a history of a severe allergic or systemic reaction following a prior dose of typhoid fever vaccine or any of its components should not receive the vaccine.
Persons with a moderate or severe acute illness should postpone vaccination.
Persons with typhoid fever or who are chronic carriers of it should not receive the vaccine.
A pregnant woman should receive the typhoid fever vaccine only if it is clearly needed.
Injected typhoid vaccines
The ViCPS form is not recommended for children less than 2 years old. The parenteral inactivated form of the vaccine is effective for children as young as 6 months old.
Oral typhoid vaccine
Children less than 6 years old should not receive the vaccine.
Persons who are immuno-compromised should not take this vaccine.
Persons with fever, persistent diarrhea, or vomiting should not receive this vaccine.
Persons who are on medications to kill bacteria, viruses, or malaria should discuss this vaccine with their healthcare provider before receiving it. Vaccination may need to be postponed.
What are the vaccine risks and side effects?
Injected typhoid vaccines
Tenderness, swelling, and redness at the typhoid fever vaccine injection site commonly start within 6 to 24 hours and last a day or two.
About half as many persons experience generalized symptoms after the Vi form than after the older vaccine. After the older vaccine, fever, muscle aches, and nausea each effect a few percent of recipients and about 10 percent get a headache.
Severe allergic reactions and other severe reactions occur rarely after either injected typhoid fever vaccine.
Oral typhoid vaccine
Although side effects may occur, they usually resolve on their own without medical care. Side effects may include hives or problems with the digestive tract (nausea, vomiting, diarrhea, abdominal cramps).
Plague vaccine and cholera vaccine often cause side effects much as the older injected typhoid fever vaccine does. Theoretically, getting these vaccines at the same time could lead to a bigger reaction. If you have time to separate these vaccinations by a week or more and still get all the vaccines you need before travel, you may have less discomfort.
This information is excerpted from the book Vaccinating Your Child: Questions and Answers for the Concerned Parent (Peachtree Publishers, Ltd., 2000). The book’s authors are Dr. Sharon G. Humiston, a pediatrician and clinical researcher at the CDC and the University of Rochester, and Cynthia Good, an award-winning journalist and host of the television show “Good for Parents”.